Zombie Strains, Part I

The volume of fiction on zombies has created a number of misconceptions as to the capabilities, capacities, and categories of zombies. Nonetheless, there have been multiple strains (or, alternatively, species) of zombies which have emerged.

Ambulatory or “Common” Zombie

Ambulatory or common zombies are generally considered to be the easiest to both combat and contain. Common zombies have extremely low land speed and limited sensory capacity. As such, they tend to cluster in large groups and only go after prey which passes within immediate visual range.
The great danger of ambulatory zombies is that they tend to infest areas for long periods of time. Often times such clusters last until either their muscles rot or they "starve." Their great strength and cluster-instinct means that common zombies can easily overwhelm any person who engages them at close-range. Furthermore, a person who takes refuge in a building can find themselves surrounded by zombies and starved out.
Nonetheless, common zombies can be easily combated and controlled by a zombie protocol team so long as the team controls their encounter area and does not engage them at close range. Clear avenues of escape are crucial.
Permanent bases designed to halt common zombies should have large cement walls which cannot be seen over. Ideally, such walls would have internal walkways to allow teams to fight from the walls.

Animus or “Predator” Zombie

Far more dangerous than the ambulatory zombie, the animus zombie are those corpses who have been reanimated before rigor mortis has set in. Unlike common zombies, predator zombies move with extreme quickness and physical skill. They retain the same strength as ambulatory zombies, but can run at a land speed that tends to exceed the average human. Furthermore they can climb walls and break barriers.
Animus zombies tend to be more likely to attempt to “sate” their hunger, generally believed to be due to the fact that they consume great quantities of energy to continue such highly active hunting cycles. Because of this, the predator zombies often actively hunt prey, turning on animals and existing meat supplies. Their sensory ranges can be quite high; some encounters indicate that animus zombies have heightened senses of smell.
Defensive tactics are generally recommended against animus zombies. They do not necessarily use advanced tactics, however a large group of predator zombies can easily overwhelm, destroy, and convert a protocol team which does not institute layered defenses and keep an open lane of retreat. As such, it is recommended that any team facing animus zombies institute combined arms fire at multiple ranges.
Permanent bases against animus zombies must have multiple layers of walls, ideally each of which will incorporate barbed wire and/or pitfalls.

Contagion or “Plague” Zombie

There exists some debate as to whether contagion zombies are a separate strain or simply a variation on other strains. Contagion zombies are noted for carrying a virulent strain of some disease. Certain encounters have shown contagion zombies which carry only a particularly deadly fever virus. However, others have shown that the zombies pass on the virus which creates other zombies; infection not only kills the victim but also reanimates them.
The capabilities, hunting patterns, and sensory ranges of contagion zombies varies, further adding to the argument that they are a sub-strain.
Protocol Teams which combat contagion zombies must, at all costs, avoid close combat. Any cut or scratch from a contagion zombie will spread the disease, and some project a small airborne cloud which allows for non-contact transmission of the disease. Air filtration masks are crucial, and constant hydration (from purified water) and vitamin C intake may help offset airborne infection. Failure to strictly adhere to these precautions can lead to the utterly abhorrent situation in which one comrade must kill another to prevent his or her reanimation.
It is highly recommended that any casualties or corpses be burned. Permanent structures designed to fight contagion zombies, by necessity, should have air filtration systems and medical bays.

Mutant or “Government-Enhanced” Zombie

The phrase “government-enhanced” zombies is a term-of-art used to cover any set of zombies which have been created, enhanced, or otherwise modified by a human entity. Why a person or entity would want to enhance zombies is beyond most; indeed, such experiments have in the past almost entirely backfired against the creator, causing enormous losses of life and capital.
Future installments will detail the various types of mutant zombies which exist, as such teams must demonstrate resourcefulness and caution when dealing with them. Popular culture references depict zombie “experiments” being released in controlled zones. This is often not the case. Instead, the mutant zombies usually arise because of an outbreak. In such an instance, protocol teams are instructed to set up quarantine areas and alert officials as soon as possible.